The Spectrum Application (RF Measurements)
R&S
®
FPL1000
102
User Manual 1178.3370.02 ─ 09
Prerequisite
Precise frequency measurements require a precise reference frequency. Therefore, an
external reference frequency from the signal generator is used. Connect the signal
generator's "Ref OUT" connector to the analyzer's "Ref IN" connector.
1. Select [PRESET] to reset the instrument.
2. Set the center frequency to
128
MHz
.
3. Set the frequency span to
1
MHz
.
4. Select "Setup" > "Reference" > "External Reference 10 MHz" to activate the exter-
nal reference frequency.
5. Select [MKR] to activate marker 1 and automatically set it to the maximum of the
trace.
The level and the frequency of the marker are displayed in the marker results in the
diagram or the marker table.
6. Select [MKR FUNC] > "Signal Count" to activate the signal counter.
The result of the signal counter is displayed in the marker results.
7. If necessary, increase the resolution of the signal counter by selecting "Signal
Count Resolution" (in the "Signal Count" menu).
Prerequisites for using the internal signal counter
In order to obtain a correct result when measuring the frequency with the internal sig-
nal counter, an RF sinusoidal signal or a spectral line must be available. The marker
must be located more than 25
dB above the noise level to ensure that the specified
measurement accuracy is adhered to.
7.2.1.4
Measurement Example – Measuring Levels at Low S/N Ratios
The minimum signal level a signal analyzer can measure is limited by its intrinsic noise.
Small signals can be swamped by noise and therefore cannot be measured. For sig-
nals that are just above the intrinsic noise, the accuracy of the level measurement is
influenced by the intrinsic noise of the R&S
FPL1000.
The displayed noise level of a signal analyzer depends on its noise figure, the selected
RF attenuation, the selected reference level, the selected resolution and video band-
width and the detector.
For details see:
●
Chapter 7.5.1.2, "RF Attenuation"
●
Chapter 7.5.1.1, "Reference Level"
●
Chapter 7.6.1.1, "Separating Signals by Selecting an Appropriate Resolution Band-
width"
●
Chapter 7.6.1.2, "Smoothing the Trace Using the Video Bandwidth"
●
"Mapping Samples to sweep Points with the Trace Detector"
Measurements and Results
